Compound semiconductor integrated circuit and method to fabricate same

Abstract

A structure includes a substrate having a surface and a first transistor disposed in a first region supported by the surface of the substrate. The first transistor has a channel formed in a first compound (Group III-V) semiconductor having a first energy bandgap. The structure further includes a second transistor disposed in a second region supported by the substrate. The second transistor has a channel formed in a second compound (Group III-V) semiconductor having a second energy bandgap that is larger than the first energy bandgap. In one embodiment the first compound semiconductor is a layer that overlies a first portion of the surface of the substrate and the substrate is the second compound semiconductor. In another embodiment the second compound semiconductor is provided as a second layer that overlies a second portion of the surface of the substrate. Methods to form the structure are also disclosed.

What is claimed is: 
     
       1. A method performed during fabrication of an integrated circuit, comprising:
 providing a compound semiconductor substrate comprising a compound semiconductor material comprising a Group III-V compound semiconductor material having a large bandgap energy, the large bandgap energy being greater than about 1 eV, the compound semiconductor substrate having a top surface, and the top surface having a first portion and a second portion positioned laterally adjacent to and level with the first portion; 
 forming a compound semiconductor layer immediately adjacent to the second portion of the top surface of the compound semiconductor substrate, the compound semiconductor layer comprising an additional compound semiconductor material having a small bandgap energy, the small bandgap energy being smaller than the large bandgap energy; and 
 forming a first transistor and a second transistor,
 the first transistor being formed so as to have a first channel positioned laterally between first source and drain regions and a first gate on the first channel, the first channel and the first source and drain regions being entirely within the compound semiconductor substrate immediately below the first portion of the top surface, and 
 the second transistor being formed so as to have a second channel positioned laterally between second source and drain regions and a second gate on the second channel, the second channel and the second source and drain regions being entirely within the compound semiconductor layer above the second portion of the top surface and the second gate being immediately adjacent to the compound semiconductor layer. 
 
 
     
     
       2. The method of  claim 1 , the additional compound semiconductor material comprising a second Group III-V compound semiconductor material that is different from the Group III-V compound semiconductor material of the compound semiconductor substrate. 
     
     
       3. The method of  claim 1 , the compound semiconductor material comprising a binary Group III-V compound semiconductor material, and the additional compound semiconductor material comprising a tertiary or a quaternary Group III-V compound semiconductor material. 
     
     
       4. The method of  claim 1 , the first transistor comprising a planar FET, and the second transistor comprising a FinFET. 
     
     
       5. A method performed during fabrication of an integrated circuit, comprising:
 providing a compound semiconductor substrate comprising a compound semiconductor material comprising a Group III-V compound semiconductor material having a first large bandgap energy, the first large bandgap energy being greater than about 1 eV, the compound semiconductor substrate having a top surface, and the top surface having a first portion and a second portion positioned laterally adjacent to and level with the first portion; 
 depositing a first compound semiconductor layer immediately adjacent to the first portion of the top surface of the compound semiconductor substrate, the first compound semiconductor layer comprised of a first additional compound semiconductor material that is different from the compound semiconductor material and has a second large bandgap energy, the second large bandgap energy being greater than about 0.75 eV; 
 depositing a second compound semiconductor layer immediately adjacent to the second portion of the top surface of the compound semiconductor substrate, the second compound semiconductor layer being physically separated from the first compound semiconductor layer and comprising a second additional compound semiconductor material having a small bandgap energy, the small bandgap energy being equal to or less than about 0.75 e V; and 
 forming a first transistor and a second transistor,
 the first transistor being formed so as to have a first channel positioned laterally between first source and drain regions and a first gate on the first channel, the first channel and the first source and drain regions being entirely within the first compound semiconductor layer immediately adjacent to the first portion of the top surface and the first gate being immediately adjacent to the first compound semiconductor layer, 
 the second transistor being formed so as to have a second channel positioned laterally between second source and drain regions and a second gate on the second channel, the second channel and the second source and drain regions being entirely within the second compound semiconductor layer immediately adjacent to the second portion of the top surface and the second gate being immediately adjacent to the second compound semiconductor layer. 
 
 
     
     
       6. The method of  claim 5 , the compound semiconductor material, the first additional compound semiconductor material and the second additional compound semiconductor material comprising different Group III-V compound semiconductor materials. 
     
     
       7. The method of  claim 5 , the compound semiconductor material and the first additional compound semiconductor material comprising different binary Group III-V compound semiconductor materials, and the second additional compound semiconductor material comprising a tertiary or a quaternary Group III-V compound semiconductor material. 
     
     
       8. The method of  claim 5 , the first transistor being one of a planar FET or a FinFET, and the second transistor being one of a planar FET or a FinFET. 
     
     
       9. The method of  claim 5 , the first compound semiconductor layer and the second compound semiconductor layer being epitaxially deposited over the top surface of the compound semiconductor substrate. 
     
     
       10. A method performed during fabrication of an integrated circuit, comprising:
 providing a compound semiconductor substrate comprising a compound semiconductor material comprising a Group III-V compound semiconductor material having a large bandgap energy, the large bandgap energy being greater than about 1 eV, the compound semiconductor substrate having a top surface, and the top surface having a first portion and a second portion positioned laterally adjacent to and level with the first portion; 
 forming a mask layer to cover the first portion of the top surface of the compound semiconductor substrate; 
 depositing a compound semiconductor layer immediately adjacent to the second portion of the top surface of the compound semiconductor substrate, the compound semiconductor layer comprising an additional compound semiconductor material comprising an additional Group III -V compound semiconductor material having a small bandgap energy, the small bandgap energy being equal to or less than about 0.75 eV; 
 removing the mask layer from the first portion of the top surface of the compound semiconductor substrate; and 
 forming a first transistor for use in at least one of memory and input/output circuitry and a second transistor for use in logic circuitry,
 the first transistor being formed so as to have a first channel positioned laterally between first source and drain regions and a first gate adjacent to the first channel, the first channel and the first source and drain regions being entirely within the compound semiconductor substrate immediately below the first portion of the top surface, 
 the second transistor being formed so as to have a second channel positioned laterally between second source and drain regions and a second gate adjacent to the second channel, the second channel and second source and drain regions being entirely within the compound semiconductor layer immediately adjacent to the second portion of the top surface and the second gate being immediately adjacent to the compound semiconductor layer. 
 
 
     
     
       11. The method of  claim 10 , the Group III-V compound semiconductor material comprising a binary Group III-V compound semiconductor material, and the additional Group III-V compound semiconductor material comprising a tertiary or a quaternary Group III-V compound semiconductor material. 
     
     
       12. The method of  claim 10 , the first transistor being a planar FET and the second transistor being a planar FET. 
     
     
       13. The method of  claim 10 , the first transistor being a planar FET and the second transistor being a FinFET. 
     
     
       14. The method of  claim 10 , the first transistor being a FinFet and the second transistor is a planar FET. 
     
     
       15. The method of  claim 10 , the first transistor being a FinFET and the second transistor being a FinFET. 
     
     
       16. The method of  claim 1 , the compound semiconductor material comprising InP. 
     
     
       17. The method of  claim 5 , the compound semiconductor material comprising InP. 
     
     
       18. The method of  claim 10 , the compound semiconductor mate rial comprising InP.